Prostate enlargement is a widespread phenomenon developed in more than half men over age 50. By age 80, about 80% of men have enlarged prostates. The prostate enlargement is thought to be related to hormonal disorders typical to the age, and is termed Benign Prostatic Hyperplasia or BPH. In a minority of the cases, the prostate enlargement involves prostate cancer.
Whatsoever be the cause, enlarged prostate may lead to bladder control problems. This is because the prostate gland encircles the urethra beneath the bladder neck. An enlarged prostate exerts pressure on the urethra which may deform its shape and reduce its cross sectional area. In acute circumstances, a total blockage of the urethra might occur.
A quantitative diagnosis of the urethral blockage can help in early detection of prostate problems, which in turn allows for anticipating medication or other appropriate treatment. In cases where bladder control problems exist already, a quantitative diagnosis may help in determining severity of the case and in monitoring the effect of the treatment procedures been taken.
From a broader perspective, a quantitative diagnosis of urethral blockage is only one of several common tests taken during the somewhat complicated process of screening and diagnosing for Lower Urinary Tract Symptoms (LUTS). Lower Urinary Tract Symptoms may involve several factors, including disorders in the somatic nervous system, in the bladder/urethral autonomic nervous system, in the detrusor and in the sphincter muscles, and more. Said screening process is therefore a must for distinguishing between the plurality of medical situations that may cause a patient to experience urinary problems.
Facilitating and simplifying the recognition and the quantitative diagnosis of urethral blockage may therefore be essential not only in case a blockage does exist, but also in negating its existence in the opposite case thus leading toward a correct diagnosis.
The methods commonly used for quantitative detection of prostate condition include the following techniques: a digital rectal exam to feel for prostate enlargement; cystoscopy (under local anesthetic) consisting of passing a lens into the urethra and bladder to see if any abnormalities are present; intravenous pyelogram consisting of X-ray irradiation of the urinary tract as a dye is injected into a vein that shows up tumors or blockages; ultrasound test of the prostate. The latter is generally implemented by using one of two methods: Transrectal ultrasonography (TRUS) that uses a rectal probe for assessing the prostate, and can sometimes detect cancer; and Transabdominal ultrasonography that uses a device placed over the abdomen. Comparing TRUS with Transabdominal ultrasonography, TRUS is significantly more accurate for determining prostate volume or the degree of urethral blockage, while Transabdominal ultrasonography can give an accurate measure of postvoid residual urine and is less invasive and expensive than TRUS.
Yet another known technique for quantitative detection of prostate condition is based on the uroflowmetry test. This is aimed at determining whether the bladder is obstructed, by electronically measuring the speed of urine flow. The test, however, cannot determine the cause of obstruction, which can be due not only to BPH, but possibly also to abnormalities in the urethra, weak bladder muscles, or other causes. According to this technique, the patient is instructed not to urinate for several hours before the test and to drink plenty of fluids so he has a full bladder and a strong urge to urinate. To perform this test, a patient urinates into a special toilet equipped with an uroflowmeter. It is important that the patient remains still while urinating to help ensure accuracy, and that he urinates normally and does not exert strain to empty his bladder or attempt to retard his urine flow. Many factors can affect urine flow, such as straining or holding back because of self-consciousness; so experts recommend then that the test be repeated at least twice. The rate of urine flow is calculated as milliliters of urine passed per second (mL/s). At its peak, the flow rate measurement is recorded and referred to as the Q[max]. The higher the Q[max], the better the patients flow rate. Men with a Q[max] of less than 12 mL/s have four times the risk for urinary retention than men with a stronger urinary flow. The Q[max] measurement is sometimes used as the basis for determining the severity of obstruction and for judging the success of treatments. It is not very accurate, however, for a number of reasons: Urine flow varies widely among individuals as well as from test to test. The patient's age must be considered. Flow rate normally decreases as men age, so the Q[max] typically ranges from more than 25 mL/s in young men to less than 10 mL/s in elderly men. The Q[max] level does not necessarily coincide with a patient's perceptions of the severity of his own symptoms.
It is appreciated that the currently used non invasive methods are incapable of individually determining a urethral blockage or performing a quantitative measurement thereof. For example, uroflowmetry may not necessarily teach of a blockage and/or of its severity unless the internal bladder pressure is also known. This is because on the one hand a low flow rate may be an indication of a detrusor problem rather than of a urethral blockage, while on the other hand a normally detected flow rate should not necessarily indicate of a normal urethra since it may result from extra abdominal/bladder pressures compensating against certain flow resistance caused by urethral blockage. Uroflowmetry combined with simultaneous measurement of internal bladder pressure is thus required in order to allow for discrimination between the different factors (i.e. the urethra flow resistance and the abdominal/bladder pressure). Internal bladder pressure measurement involves however invasive procedure—inserting a catheter into the bladder. The inconvenience and infection risks accompanied to the procedure make its use rare and appropriate for special cases only.
U.S. Pat. No. 6,063,043 discloses a passive acoustic method of detecting the presence or absence of vesicoureteral reflux in a patient. According to this technique, sound from the abdomen of the patient from a time just prior to the onset of urination in the patient is amplified, and then the presence or absence of an audio signal characteristic of vesicureteral reflux in the amplified sound is detected. The presence of the signal indicates the presence of vesicoureteral reflux in the patient.
U.S. Pat. No. 6,428,479 discloses a technique of detecting prostate abnormalities such as cancer. This technique utilizes ultrasonic determination of the in-flow kinetics of contrast agent-containing blood in the prostate and/or observation of disease-related asymmetries in the spoke-like vascular pattern of the prostate.
WO 05/067392 discloses a rectal probe adapted for ultrasound and magnetic resonance imaging of the prostate. This probe comprises an ultrasound imaging probe; an MRI probe; and a link joining the ultrasound probe and the MRI probe. The MRI probe comprises a first magnetic field source for creating a static magnetic field in an MRI imaging region outside the rectal probe, a second magnetic field source for creating a time-varying magnetic field which excites nuclei in the MRI imaging region, and a receiver for receiving NMR signals from the excited nuclei and generating MRI imaging data indicative thereof.
WO 05/004726 describes a method of analyzing a Doppler flow image of a region containing a tumor, wherein the region includes a pelvis, adnexa uteri, a uterus, an ovary, a breast, a prostate, a hepatic artery, a liver and the like. According to this technique, the Doppler flow image is represented as a three-dimensional flow representation; and at least one parameter characterizing a velocity spectrum of the three-dimensional flow representation is calculated, so as to determine malignancy likelihood of the tumor; thereby analyzing the Doppler flow image.
U.S. Pat. No. 6,863,654 discloses a method of identifying a patient's urethral anatomic course in real time for the precise placement of a treatment element into the patient's prostate. This technique utilizes a catheter containing an external, inflatable imaging bladder. The catheter is introduced into a urethra of the patient until the image bladder is generally aligned with a treatment site of the prostate. An imaging probe of an imaging device is operatively positioned relative to the treatment site of the prostate and proximate portions of the urethra. The imaging device is activated so as to obtain a real time image of the treatment site of the prostate. The imaging bladder is filled when needed to essentially turn on and define an acoustic interface between the interior of the imaging bladder and the urethral wall. A boundary of the urethra is identified and viewed at the acoustic interface during placement of the treatment element so as to identify proper positioning thereof relative to the urethra.
RU 2224464 discloses a method using ultrasonic Doppler echometric examination of regional prostate blood circulation. Quantitative and qualitative indices are determined. According to this technique, chronic prostatitis is diagnosed by detecting pulsation index greater than 1.1 and venous blood circulation less than 4.5 cm/s relative to those of practically healthy people.